[Bug c/20329] New: regression: current 3.4.4 miscompiles Linux kernel with athlon optimisations

[Bug c/20329] New: regression: current 3.4.4 miscompiles Linux kernel with athlon optimisations

[bero at arklinux dot org]

First of all, sorry for a very vague bug report, this is hard to trace down  
and I'm short on time.  
  
Compiling a Linux kernel with athlon optimisations with current gcc 3.4.4  
snapshots results in a kernel that Oopses on bootup on most (though not all)  
Athlon machines. 
 
Optimising for i686 instead of athlon "fixes" the problem; so does reverting 
to an older gcc (including older 3.4.4 snapshots). 
 
Last known good version: 3.4.4-20050127  
First known bad version: 3.4.4-20050227

-- 
           Summary: regression: current 3.4.4 miscompiles Linux kernel with
                    athlon optimisations
           Product: gcc
           Version: 3.4.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bero at arklinux dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20329

[Bug c/20329] regression: current 3.4.4 miscompiles Linux kernel with athlon optimisations

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-03-05 07:43 -------
We really need a small example code to figure this one out.  This could be stilll a linux kernel bug.  I 
know for a fact the kernel does not follow the aliasing rules at all.

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           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pinskia at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20329

[Bug middle-end/20329] regression: current 3.4.4 miscompiles Linux kernel with athlon optimisations

[bero at arklinux dot org]

------- Additional Comments From bero at arklinux dot org  2005-05-21 14:30 -------
I haven't been able to find a short piece of code triggering this problem, but 
using a fairly stupid script ("while true; do check out older version; 
compile; see if problem persists; done"), I've found the problem appears with 
the fix for target/19803. 
 
Reverting this patch fixes the problem. 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW
     Ever Confirmed|                            |1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20329

[Bug middle-end/20329] [3.4 regression]: current 3.4.4 miscompiles Linux kernel with athlon optimisations

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-05-21 14:37 -------
(In reply to comment #2)
> Reverting this patch fixes the problem. 

There is a latent bug somewhere else.
We still need a testcase.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |WAITING
            Summary|regression: current 3.4.4   |[3.4 regression]: current
                   |miscompiles Linux kernel    |3.4.4 miscompiles Linux
                   |with athlon optimisations   |kernel with athlon
                   |                            |optimisations
   Target Milestone|---                         |3.4.5


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20329

[Bug middle-end/20329] [3.4 regression]: current 3.4.4 miscompiles Linux kernel with athlon optimisations

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-08-17 03:09 -------
No feedback in 3 months (T-5 days).

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20329